The plot of square root of frequency of X-ray emitted against atomic number led to suggestion of which law/rule?
Periodic law
Modern periodic law
Hund's rule
Newland's law
B.
Modern periodic law
Moseley, gave modern periodic law. He showed that atomic number is more fundamental property of an element than its atomic mass as follows.
"The square root of the frequency of a line (of X-ray spectrum) is related to the atomic number Z of the target material as,
√V = a (Z- b)
where, a= proportionality constant
Z = atomic number
b = another constant
L it has the same value for all the lines of X-rays spectrum.
If average velocity of a sample of gas molecules at 300 K is 5 cm s-1, what is RMS velocity of same sample of gas molecules at the same temperature? (Given, α: u: v = 1:1.224: 1.127)
6.112 cm/s
4.605 cm/s
4.085 cm/s
5.430 cm/s
20 mL solution of 0.1 M ferrous sulphate was completely oxidised using a suitable oxidising agent. What is the number of electrons exchanged?
1.204 x 1022
193
1930
1.204 x 1021
The volume of oxygen evolved at STP by decomposition of 0.68 g '20 volume' hydrogen peroxide solution is
2.24mL
22.4mL
224mL
2240mL
What is the molality of a solution containing 200 mg of urea (molar mass 60 g mol-1) dissolved in 40 g of water?
0.0825
0.825
0.498
0.0013
The work done when two mole of an ideal gas is compressed form a volume of 5 m3 to 1 dm3 at 300 K, under a pressure of 100 kPa is
499.9kJ
-499.9 kJ
-99.5 kJ
42495 kJ
Assuming enthalpy of combustion of hydrogen at 273 K is -286 kJ and enthalpy of fusion of ice at the same temperature to be +6.0 kJ, calculate enthalpy change during formation of 100 g of ice.
+1622 kJ
- 1622 kJ
+292 kJ
- 292 kJ
The product of molar concentrations of hydrogen ions and hydroxide ions in a 0.01 M aqueous solution of sodium chloride is known as
hydrolysis constant of salt
dissociation constant of acid
dissociation constant of base
ionic product of water